1. Field of the Invention
The invention relates to a microphone apparatus, and in particular to a small array microphone apparatus and beam forming method thereof.
2. Description of the Related Art
In FIG. 1, two omni-directional microphones 10 and 12 are put approximately on a line (X coordinate) and a near-end talker 14 vertically faces to the line formed by the two omni-directional microphones 10 and 12.
The bi-directional microphone outputs signals with a bi-directional pattern 16 as depicted in FIG. 1. The bi-directional pattern 16 has two lobes 16a and 16b pointing left and right on line X. Because beam forming using the bi-directional pattern 16 for noise suppression can only form a so-called “pie” beam, the bi-directional pattern 16 is appropriate for suppressing noise from left and right directions, but not for noise from up and down directions. Therefore, bi-directional pattern 16 is not adequate for many applications such as cell phones, smart phones and other portable communication devices, etc. due to their inability to suppress noise from the bottom of such communications devices.